1. Field of the Invention
The present invention relates to an apparatus for profiling an article such as a grinding wheel, having a cylindrical face and rounded corners joining both ends thereof, in template tracing manner.
2. Brief Description of the Prior Art
Conventionally, a grinding wheel for grinding pins of a crankshaft is dressed, in template tracing manner, to have a cylindrical face and rounded corners joining both ends thereof. In such dressing, a stylus is moved to trace a template which is formed with a straight portion and rounded corners, joining both ends thereof, so as to correspond to the profile of the grinding wheel and further, with steep slopes joining the rounded corners. However, excessive load is exerted upon the template and the stylus when the same ascends each steep slope, and this makes smooth and precise tracing of the stylus difficult.
For this reason, an attempt has heretofore been made to cause the stylus to trace the template upon movement only in a direction descending the steep slope of the template. In a known dressing device which embodied such an attempt effect, the stylus, when moved in an ascending direction, is first withdrawn to a little lower position than the height of the straight portion of the template prior to traverse movement and is then traversed toward and along the straight portion of the template. However, the stylus impacts upon a point on each rounded corner in the vicinity of the straight portion when coming into contact therewith. This not only causes a dressing tool to bite the grinding wheel, but also accelerates partial wear of the stylus and the template, thus resulting in deterioration of machining accuracy.
Another type of improved dressing devices has also been known which uses two templates one for dressing process from one side to the other side and the other for dressing process from the other side to one side. Two styluses are provided therein for selective contact with the corresponding templates. Even if two templates and two styluses can be made with the same precision, however, there is effected different wear characteristic between the templates as well as between the styluses. Thus, the dressing process from one side to the other side substantially differs in dressing condition from the dressing process from the other side to the one side, so that the dressing accuracy of the grinding wheel cannot be maintained so as to be uniform and stable.